Principle: The CU aircraft Extractive Electrospray Time-of-Flight Mass Spectrometer (EESI-TOFMS) detects the chemical composition of submicron particulate matter by simultaneous dissolution of the aerosol and soft ionization of its molecular components in an electrospray, followed by detection using time-of-flight mass spectrometry. When operated with positive ion polarity analytes are detected intact as adducts with sodium ions. When operated with negative ion polarity analytes are detected as deprotonated anions.
Aircraft Operation: Operated with positive or negative ion polarity, depending on mission goals.
Pressure-controlled EESI region with a maximum sampling altitude of 23 kft. Sensitivity can be increased for boundary layer sampling by increasing the pressure of the electrospray region.
Calibrated relative to AMS on flight days, and confirmed with absolute calibrations on maintenance days
1s time resolution with 15s background measurements every 4 min.
Data Products:
Positive ion polarity EESI(+): C6H10O5 calibrated as levoglucosan and C6H5NO4 calibrated as nitrocatechol
Negative ion polarity EESI(-): C6H5NO4 calibrated as nitrocatechol
Additional species under development. Species of interest for specific campaigns can be tested and calibrated for.
Detection Limits (1s):
C6H10O5 as levoglucosan: 200 ng sm-3
C6H5NO4 as nitrocatechol: 20ng sm-3 EESI(-), 400 ng sm-3 EESI(+)